STAT3 and hepatocellular carcinoma: Moreover, in orthotopic implantation xenograft tumor of MHCC97-L, HMH-exosomes (HCC-LM3 exosomes and MHCC97-H exosomes) significantly enhanced nuclear STAT3 phosphorylation and cytoplasmic OPN expression while LMH exosomes (HepG2 exosomes) or PBS could not (Fig. 5e).